How many people realistically are willing to write vimscript plugins, vs how many people realistically are willing to write Lua? I know personally, after wresting with vimscript for a couple of days I'd never touch it again, but Lua is nice.
In a vacuum where there was no need for legacy vim support (lets say vim integrated lua), I can't imagine anyone but a small minority preferring vimscript over lua. My argument isn't that nobody programs vimscript, it's that hardly anyone does it by choice.
